The present invention relates to an apparatus for continuously winding up a thread.
In the production of synthetic threads it is common that at the end of the process the threads are wound up to form a bobbin. To prevent process interruptions in melt spinning, the threads are continuously wound up to form a bobbin, without significant interruptions. The devices provided for a continuous winding operation comprise two winding spindles which are held in a projecting manner on a rotary table. When turning the rotary table, the winding spindles are guided alternately to a winding region and a changing region. For example, such an apparatus has been described in DE 197 43 278.
The apparatus described in DE 197 43 278 includes a movable changing device, which can be guided in the area between the two winding spindles in order to transfer the thread between the winding spindles. In this context, it is important that the thread can be received by a catching device which is arranged at the winding spindle receiving the thread. For this purpose, the changing device comprises at least a deflecting thread guide and a feeding thread guide. After exchanging the winding spindles, the changing device is moved in the thread running direction between the winding spindle dispensing the thread and the winding spindle receiving the thread. In the process, the thread is still wound onto the bobbin held on the winding spindle dispensing the thread. In a deflecting position of the changing device, the deflecting thread guide catches the thread and holds it at a distance from the winding spindle, which receives the thread and which has on its circumference an empty tube. Then, via the feeding thread guide, the thread is positioned after it has been released in a changing device, and through a backward movement of the changing device, the thread is guided into the catching device of the receiving winding spindle. To this end, the thread is caught by a curved hook of the feeding thread guide and pulled into the catching device.
However, this device has the disadvantage that the entire changing device has to be swiveled out of the deflecting position to be able to feed the thread into the catching device. Because of the fact that the device as a whole has to be activated and moved, long changing times for transferring the thread are inevitable. In addition, the pulling process exposes the thread to considerable mechanical stress, resulting in filament strands that are unraveled and damaged. Especially with so-called BCF yarns, the unraveling of the thread poses a problem because at some places the crimping is defective. In this respect, the thread segments wound onto a full bobbin as so-called wrapper fibers during the process of transferring the thread cannot be used for further processing.
EP 0 521 816 discloses another apparatus for continuously winding up a thread. In this apparatus, the changing device is held laterally to the winding spindles and interacts with a movable deflection rod, which can be pivoted from an opposite side in the thread running direction between the two winding spindles, thus deflecting the thread in the direction of the changing device. The changing device comprises a changing plate and a feeding thread guide, which is designed as a catch wing and which guides a thread running at the changing plate parallel to the winding spindle. To transfer the thread to a catching device of the winding spindle receiving the thread, the changing device is pivoted in the direction of the winding spindles in such a way that the thread is guided in contact to an empty tube of the receiving winding spindle and, through movement of the feeding thread guide, it is guided into an axially offset thread-catching slit. In this device, the contact with the empty tube exposes the thread to considerable mechanical stress, which inevitably results in damage. As a result, the wrapper fibers wound onto the full bobbin during the process of transferring the thread cannot be used for further processing.